Our team coverage of last nights severe storms continues. We’re speaking with a hail expert.
Victor Gensini, professor and meteorology program advisor at NIU, joins the show.

One storm near Kankakee, Illinois, produced a large, destructive tornado Tuesday. It also produced what will likely go down as a record hailstone for the state. 

It looked like something out of a weather textbook. Let’s show you the moments we knew destruction was happening. 

The hail

We’ll start with the hail. 

I was getting ready for bed around 7 p.m. EDT Tuesday (since I’m up before 2 a.m.), and I checked my radar app. 

The image below is what I saw. 

A textbook supercell (rotating thunderstorm) was moving south of Chicago, but there was a unique feature that caught my attention. 

I’ve highlighted that in the image. It doesn’t look like much, but it’s a huge teller of large hail. It’s called a TBSS, or three body scatter spike. 

As the radar beam hits hailstones, it gets scattered three different times. That results in the appendage you see on radar extending off the storm.

Moments later, reports came in of hail that was baseball-sized and larger. One such report could break the state’s record for largest hailstone. 

The report suggested a hailstone of 6 inches in diameter.

According to NOAA’s National Centers for Environmental Information, this would break Illinois’ previous record for largest hailstone – and by a long shot.

The largest hailstone on record in the U.S. happened in South Dakota, and it was measured at 8 inches in diameter. 

Insane!

The tornado

While it takes time to assess the damage and come up with a rating, there was zero doubt that a tornado spawned from this storm too. 

It’s common during tornadoes for there to be hail on the northern flank of the storm. It’s called the “hail core,” and it is a result of rapidly rising air. 

In terms of the actual tornado, it became evident that one was active when looking at radar. 

A hook echo is commonly seen in supercell thunderstorms. It’s an indication of warm air flowing into the storm, while cold air flows down its rear flank. This is your rotational aspect of the storm that extends down to the surface.

The air spins rapidly and – eventually – it picks up debris. This can show up as a ball on the southern tip of the storm. 

Every bit of this storm was something out of a meteorology textbook – a marvel for those who admire the atmosphere, but a nightmare for those at ground level enduring its fury.

Central Illinois is expected to be hit with tornado alerts Tuesday afternoon and evening, with the highest risk between 6 and 10 p.m.

The National Weather Service announced on X that a Tornado Watch is 95% likely in east-central Illinois through 4:30 p.m. The potential storm is forecast to reach a peak intensity of 2-3.5 inch hail, 55-70 mph winds and 120-150 mph tornadoes.

Here’s how to stay updated on weather alerts in your area.

How to sign up for weather alerts in Illinois

Most residents throughout Illinois will automatically receive Wireless Emergency Alerts on their mobile phones from the NWS, warning them of potentially dangerous weather in their area. These will look like normal text messages and will typically show the type and time of the alert, any action you should take and the agency issuing the alert. 

Other sources of information include NOAA Weather Radio, the Storm Prediction Center’s live map of nationwide tornado watches and the Emergency Alert System on radio and TV broadcasts.

Residents can also sign up for text alerts through their local county emergency management agency, such as NotifyChicago.

Sign up for USA TODAY Network weather alerts

Illinois residents can sign up for alerts from the USA TODAY Network to receive texts about current storms and weather events in their area.

Tornado watch vs warning

The NWS explains the difference between the varying tornado alert terminology on its website.

A tornado watch means tornadoes are possible in the area, while a tornado warning means a twister has been sighted or indicated by the weather radar. A tornado emergency is the most severe alert, meaning a violent tornado has touched down in the area.

The website uses the phrases “be prepared,” “take action” and “seek shelter immediately” to summarize the three alerts.

Central Illinois weather radar

Chicago weather radar